Add post-timer labels (#1) (#30)

* Add post-timer labels (#1)

* add post-timer label support to summary

no reason to add a parameter into the first nested function, since that's only used in Summary.labels

* allow startLabels to be undefined

* add post-timer label support for gauges and histograms

* add extend to gauge.js

* add gauge tests (#2)

* add gauge tests

* add histogram tests

* add summary tests

* add timer + label documentation to readme

* add comments

* lint files

README.md

@@ -120,6 +120,18 @@ gauge.set({ method: 'GET', statusCode: '200' }, 100); // 1st version, Set value
 gauge.labels('GET', '200').set(100); // 2nd version, Same as above
 ```
 
+It is also possible to use timers with labels, both before and after the timer is created:
+```js
+var end = startTimer({ method: 'GET' }); // Set method to GET, we don't know statusCode yet
+xhrRequest(function(err, res) {
+	if (err) {
+		end({ statusCode: '500' }); // Sets value to xhrRequest duration in seconds with statusCode 500
+	} else {
+		end({ statusCode: '200' }); // Sets value to xhrRequest duration in seconds with statusCode 200
+	}
+});
+```
+
 #### Pushgateway
 
 It is possible to push metrics via a [Pushgateway](https://github.com/prometheus/pushgateway). 

lib/gauge.js

@@ -7,6 +7,7 @@ var register = require('./register');
 var type = 'gauge';
 
 var isNumber = require('./util').isNumber;
+var extend = require('util-extend');
 var createValue = require('./util').setValue;
 var getProperties = require('./util').getPropertiesFromObj;
 var getLabels = require('./util').getLabels;
@@ -133,13 +134,13 @@ function setToCurrentTime(labels) {
 	};
 }
 
-function startTimer(labels) {
+function startTimer(startLabels) {
 	var gauge = this;
 	return function() {
 		var start = new Date();
-		return function() {
+		return function(endLabels) {
 			var end = new Date();
-			gauge.set(labels, (end - start) / 1000);
+			gauge.set(extend(startLabels || {}, endLabels), (end - start) / 1000);
 		};
 	};
 }

lib/histogram.js

@@ -107,13 +107,13 @@ Histogram.prototype.labels = function() {
 	};
 };
 
-function startTimer(labels) {
+function startTimer(startLabels) {
 	var histogram = this;
 	return function() {
 		var start = new Date();
-		return function() {
+		return function(endLabels) {
 			var end = new Date();
-			histogram.observe(labels, (end - start) / 1000);
+			histogram.observe(extend(startLabels || {}, endLabels), (end - start) / 1000);
 		};
 	};
 }

lib/summary.js

@@ -136,16 +136,17 @@ Summary.prototype.labels = function() {
 	};
 };
 
-function startTimer(labels) {
+function startTimer(startLabels) {
 	var summary = this;
 	return function() {
 		var start = new Date();
-		return function() {
+		return function(endLabels) {
 			var end = new Date();
-			summary.observe(labels, (end - start) / 1000);
+			summary.observe(extend(startLabels || {}, endLabels), (end - start) / 1000);
 		};
 	};
 }
+
 function validateInput(name, help, labels) {
 	if(!help) {
 		throw new Error('Missing mandatory help parameter');

test/gaugeTest.js

@@ -87,6 +87,23 @@ describe('gauge', function() {
 			expectValue(1);
 			clock.restore();
 		});
+		it('should be able to start a timer and set labels afterwards', function(){
+			var clock = sinon.useFakeTimers();
+			var end = instance.startTimer();
+			clock.tick(1000);
+			end({ 'code': 200 });
+			expectValue(1);
+			clock.restore();
+		});
+		it('should allow labels before and after timers', function(){
+			instance = new Gauge('name', 'help', ['code', 'success']);
+			var clock = sinon.useFakeTimers();
+			var end = instance.startTimer({ 'code': 200 });
+			clock.tick(1000);
+			end({ 'success': 'SUCCESS' });
+			expectValue(1);
+			clock.restore();
+		});
 	});
 
 	function expectValue(val) {

test/histogramTest.js

@@ -140,6 +140,29 @@ describe('histogram', function() {
 			expect(res.value).to.equal(1);
 			clock.restore();
 		});
+
+		it('should start a timer and set labels afterwards', function(){
+			var clock = sinon.useFakeTimers();
+			var end = instance.startTimer();
+			clock.tick(500);
+			end({ 'method': 'get' });
+			var res = getValueByLeAndLabel(0.5, 'method', 'get', instance.get().values);
+			expect(res.value).to.equal(1);
+			clock.restore();
+		});
+
+		it('should allow labels before and after timers', function(){
+			instance = new Histogram('histogram_labels', 'Histogram with labels fn', [ 'method', 'success' ]);
+			var clock = sinon.useFakeTimers();
+			var end = instance.startTimer({ 'method': 'get' });
+			clock.tick(500);
+			end({ 'success': 'SUCCESS' });
+			var res1 = getValueByLeAndLabel(0.5, 'method', 'get', instance.get().values);
+			var res2 = getValueByLeAndLabel(0.5, 'success', 'SUCCESS', instance.get().values);
+			expect(res1.value).to.equal(1);
+			expect(res2.value).to.equal(1);
+			clock.restore();
+		});
 	});
 
 	function getValueByName(name, values) {

test/summaryTest.js

@@ -3,6 +3,7 @@
 describe('summary', function() {
 	var Summary = require('../index').summary;
 	var expect = require('chai').expect;
+	var sinon = require('sinon');
 	var instance;
 
 	beforeEach(function() {
@@ -156,5 +157,80 @@ describe('summary', function() {
 			};
 			expect(fn).to.throw(Error);
 		});
+
+		it('should start a timer', function() {
+			var clock = sinon.useFakeTimers();
+			var end = instance.labels('GET', '/test').startTimer();
+			clock.tick(1000);
+			end();
+			var values = instance.get().values;
+			expect(values).to.have.length(3);
+			expect(values[0].labels.method).to.equal('GET');
+			expect(values[0].labels.endpoint).to.equal('/test');
+			expect(values[0].labels.quantile).to.equal(0.9);
+			expect(values[0].value).to.equal(1);
+
+			expect(values[1].metricName).to.equal('summary_test_sum');
+			expect(values[1].labels.method).to.equal('GET');
+			expect(values[1].labels.endpoint).to.equal('/test');
+			expect(values[1].value).to.equal(1);
+
+			expect(values[2].metricName).to.equal('summary_test_count');
+			expect(values[2].labels.method).to.equal('GET');
+			expect(values[2].labels.endpoint).to.equal('/test');
+			expect(values[2].value).to.equal(1);
+
+			clock.restore();
+		});
+
+		it('should start a timer and set labels afterwards', function(){
+			var clock = sinon.useFakeTimers();
+			var end = instance.startTimer();
+			clock.tick(1000);
+			end({ 'method': 'GET', 'endpoint': '/test' });
+			var values = instance.get().values;
+			expect(values).to.have.length(3);
+			expect(values[0].labels.method).to.equal('GET');
+			expect(values[0].labels.endpoint).to.equal('/test');
+			expect(values[0].labels.quantile).to.equal(0.9);
+			expect(values[0].value).to.equal(1);
+
+			expect(values[1].metricName).to.equal('summary_test_sum');
+			expect(values[1].labels.method).to.equal('GET');
+			expect(values[1].labels.endpoint).to.equal('/test');
+			expect(values[1].value).to.equal(1);
+
+			expect(values[2].metricName).to.equal('summary_test_count');
+			expect(values[2].labels.method).to.equal('GET');
+			expect(values[2].labels.endpoint).to.equal('/test');
+			expect(values[2].value).to.equal(1);
+
+			clock.restore();
+		});
+
+		it('should allow labels before and after timers', function(){
+			var clock = sinon.useFakeTimers();
+			var end = instance.startTimer({ 'method': 'GET' });
+			clock.tick(1000);
+			end({ 'endpoint': '/test' });
+			var values = instance.get().values;
+			expect(values).to.have.length(3);
+			expect(values[0].labels.method).to.equal('GET');
+			expect(values[0].labels.endpoint).to.equal('/test');
+			expect(values[0].labels.quantile).to.equal(0.9);
+			expect(values[0].value).to.equal(1);
+
+			expect(values[1].metricName).to.equal('summary_test_sum');
+			expect(values[1].labels.method).to.equal('GET');
+			expect(values[1].labels.endpoint).to.equal('/test');
+			expect(values[1].value).to.equal(1);
+
+			expect(values[2].metricName).to.equal('summary_test_count');
+			expect(values[2].labels.method).to.equal('GET');
+			expect(values[2].labels.endpoint).to.equal('/test');
+			expect(values[2].value).to.equal(1);
+
+			clock.restore();
+		});
 	});
 });